Radiographic Absorptiometry (RA) is utilized to measure volumetric bone mineral density (BMD) in the 2nd, 3rd, and 4th middle phalanges. The assignee of the present patent application has developed a technology referred to as the Osteogram™ technology to automatically generate the contour of the middle phalanges from a digital version of the 2-dimensional radiograph. The contour of the middle phalange may then be utilized to calculate the bone mineral density of the middle phalange. This BMD measure can then be utilized by health care workers to assess the risk of osteoporosis.
The middle phalange consists of two types of bones: the cortical bone and the trabecular bone. In certain applications, features of the cortical bone or features of the trabecular bone may be required because the cortical bone and the trabecular bone may respond differently to osteoporosis and aging. In other cases, the cortical bone and the trabecular bone may respond differently to different therapies.
For example, in some applications, it may be helpful to have the bone mineral density of the cortical bone and the bone mineral density of the trabecular bone instead of an integrated bone mineral density.
Unfortunately, prior art approaches are incapable or have undesirable disadvantages associated therewith. Two commonly utilized approaches to determining BMD are 1) single x-ray absorptiometry (SXA) and 2) dual x-ray absorptiometry (DXA). SXA and DXA use projectional technology and report an area density (e.g., mass per unit of projected area). Unfortunately, DXA only measures an integrated bone mineral density and is incapable for determining the specific density of the cortical bone and the trabecular bone.
A second approach is called Quantitative Computed Tomography (QCT). QCT is also a three-dimensional technology. QCT is capable of separately measuring the bone density of the cortical bone and the trabecular bone. However, the application of QCT is limited in practice due to high costs involved. For example, a single QCT procedure can cost several hundred dollars. There is also the added inconvenience and burden for the patient since the QCT procedure is not as readily available at hospitals and health care clinics as an X-ray machine due to QCT equipment's high installation and maintenance costs. The actual procedure is also more time consuming than other procedures, thereby placing a burden on both the patient and the person operating the QCT equipment. Furthermore, the QCT procedure potentially incurs a health cost because the patient is exposed to doses of radiation that are much higher than the normal X-ray.
Consequently, there remains a need in the art for a method and system for separately determining one or more features of cortical bone and the trabecular bone that overcomes the disadvantages of the prior art as set forth previously.
Moreover, determining what portions of a target bone shown in an x-ray, for example, is cortical bone tissue and what portions of a target bone shown in an x-ray, for example, is trabecular bone tissue are difficult tasks. When performed manually, this process is inaccurate, difficult to perform, and is subject to human error and bias. It would be desirable to perform these tasks automatically by using image processing software. Unfortunately, such software is not available.
Based on the foregoing, there remains a need in the art for a method and system for automatically identifying regions of trabecular bone tissue and cortical bone tissue of a target bone from a digital radiograph image that overcomes the disadvantages of the prior art as set forth previously.